1. Field of the Invention
The present invention relates to a welding helmet including an anti-blinding device to selectively control a welding operation and a grinding operation, and more particularly, to a welding helmet, which stably protects the welder's eyes and enables easy switching of an anti-blinding device from a welding operation mode to a grinding operation mode or vice versa without taking off the welding helmet (i.e. a protective mask).
2. Description of the Related Art
Generally, during a welding, cutting, or grinding operation, a welding helmet is used to protect the welder's eyes from glare and various toxic substances. Recently, a variety of kinds of safe and convenient electronic welding helmets have been developed and used. FIG. 1 is a perspective view illustrating a conventional electronic welding helmet including an anti-blinding device. As illustrated in FIG. 1, the conventional electronic welding helmet 1 includes a welding light detection anti-blinding device 2 worn on the welder's head to control exposure to light emitted from a welding or cutting torch.
The welding helmet 1, which is provided at a front surface thereof with the anti-blinding device 2, may reduce the illumination intensity of light directed to the welder's eyes using an anti-blinding plate 5. The anti-blinding plate 5 takes the form of a Liquid Crystal Display (LCD) included in the anti-blinding device 2.
Specifically, the anti-blinding device 2 further includes a photo sensor 4, such as, e.g., a photodiode attached to a front surface thereof. The photo sensor 4 is adapted to sense light emitted from a welding or cutting torch. As a control circuit mounted in the anti-blinding device 2 controls the anti-blinding plate 5 to be darkened such that the illumination intensity of light passing through the anti-blinding plate 5 is reduced, the anti-blinding device 2 may serve to protect the eyes of the welder who wears the welding helmet 1.
The above described conventional electronic welding helmet including the anti-blinding device has been developed to provide the welder with a fixed darkness degree of a liquid crystal shutter, or to change a darkness degree of the shutter to a standard level according to a welding operation environment. The conventional electronic welding helmet also enables not only control of a shutter operation to shield welding light, but also variable control of a shutter delay time to prevent blinding of the welder's eyes by light emitted from a base metal after welding. In addition, a variety of control switches or variable volume switches required for the shutter operation are provided at specific positions of the electronic welding helmet to maximize convenience of use by the welder.
However, in the case of the conventional welding light detection anti-blinding device, it is necessary for the welder to manually control On/Off of power, darkness adjustment of the liquid crystal shutter, sensitivity adjustment of the photo sensor, and the control switches or the variable volume switches for time delay. This may cause inconvenience in a welding operation.
FIG. 2 is a block diagram illustrating an electromagnetic wave detection anti-blinding device as disclosed in Korean Patent No. 0679896 that was filed and registered by the applicant of the present invention to solve the above described problems. FIG. 3 is a view illustrating a conventional electromagnetic wave detecting unit, and FIG. 4 is a flow chart illustrating operation of the electromagnetic wave detection anti-blinding device.
As illustrated, the electromagnetic wave detection anti-blinding device includes an optical detecting unit 20, an electromagnetic wave detecting unit 30, a user interface 40, a main control unit 50 and a light transmission control unit 60.
The optical detecting unit 20 serves to detect light emitted from a welding or cutting torch, and includes a filter and an amplifier. Specifically, the optical detecting unit 20 compares output of a solar cell 3 with a signal input from the photo sensor 4 thus detecting a variation in the quantity of the light. The electromagnetic wave detecting unit 30 serves to detect electromagnetic waves emitted from the welding or cutting torch. Once an electromagnetic wave sensor 31 generates a signal in response to the electromagnetic waves emitted from the welding or cutting torch, the signal is subsequently subjected to resonance and filtering processes and then, the resonated and filtered signal is compared with a preset value, thus enabling detection of electromagnetic waves having a specific bandwidth. To this end, the electromagnetic wave detecting unit 30 includes a resonator to resonate the electromagnetic waves input through the electromagnetic wave sensor 31, and a filter to remove noise of an output of the resonator. In this case, the resonator and the filter are provided on a per coil basis. For example, when first and second coils are provided, pairs of resonators and filters are arranged parallel to each other.
The electromagnetic wave sensor 31 is configured to sense the electromagnetic waves emitted from the welding or cutting torch using at least two coils L1 and L2.
Preferably, the electromagnetic wave sensor 31 includes first and second bar-shaped coils L1 and L2 arranged in the form of a cross.
The user interface 40 includes a mode selector to select any one of the optical detecting unit 20 and the electromagnetic wave detecting unit 30 and a display member to display a selected mode.
The main control unit 50 is adapted to apply an electromagnetic wave detecting unit start-up signal to the electromagnetic wave detecting unit 30 and to monitor a variation of an electromagnetic wave signal received from an output of the electromagnetic wave detecting unit 30, when optical detection is started by the optical detecting unit 20.
The main control unit 50 is preferably a microcomputer or a control circuit including the microcomputer. According to an operational sequence determined by the main control unit 50, when the optical detection unit 20 starts optical detection and transmits an output thereof to the main control unit 50, the main control unit 50 applies an electromagnetic wave detecting unit start-up signal 33 to the electromagnetic wave detecting unit 30, so as to detect the electromagnetic waves input through the electromagnetic wave sensor 31. Thereby, the main control unit 50 monitors a variation in the quantity of light based on the output of the optical detection unit 20 and a variation of electromagnetic waves based on the output of the electromagnetic wave detecting unit 30. If no variation occurs, the operation is stopped until variation is again sensed.
The light transmission control unit 60 begins to operate when power supplied from the solar cell 3 reaches a predetermined value or more, thus serving to control light transmittance of the anti-blinding plate 5 based on an output signal of the main control unit 50.
FIG. 3 is a view illustrating the user interface of the electromagnetic wave detection anti-blinding device.
The electromagnetic wave detection anti-blinding device controls a variation in the light transmittance of the anti-blinding plate 5. The user interface 40 serves to adjust mode selection and mode display, light shade and light detection sensitivity, time delay and electromagnetic wave detection sensitivity. The electromagnetic wave sensor 31 senses the electromagnetic waves emitted from the welding or cutting torch using the at least two coils L1 and L2, and the first and second bar-shaped coils L1 and L2 are arranged in the form of a cross.
The electromagnetic wave sensor 31 may be attached to an upper portion of a welding helmet. Preferably, a plurality of electromagnetic wave sensors may be attached at two or more upper and lower positions of the welding helmet.
FIG. 4 is a flow chart illustrating operation of the above described anti-blinding device. Hereinafter, operation and effects of the electromagnetic wave detection anti-blinding device will be described with reference to FIG. 4.
First, the optical detecting unit 20 detects a variation in the quantity of light emitted from the welding or cutting torch (S1). If a detection signal from the optical detecting unit 20 is input into the main control unit 50 (S2), the main control unit 50 applies the electromagnetic wave detecting unit start-up signal 33 to the electromagnetic wave detecting unit 30 (S3). The electromagnetic wave detecting unit 30 compares en electromagnetic wave signal input from the electromagnetic wave sensor 31 with a preset reference value (S10 to S40). An integral type circuit including a resistor R8 and a condenser C5 of a time constant unit performs smoothing of a signal output from the electromagnetic wave detecting unit (S50). The smoothened signal is input into the main control unit 50 and is calculated by the microcomputer or the control circuit including the microcomputer so as to detect the quantity of electromagnetic waves (S60). The main control unit 50 changes a light transmittance of the anti-blinding plate 5 according to the calculated result from the main control unit 50. Accordingly, the main control unit 50 performs an operation to protect the welder's eyes more safely by detecting and controlling light and electromagnetic waves generated during a welding operation (S70).
The welding helmet having the above described configuration, however, has a problem in that the welder must take the welding helmet off to switch the anti-blinding device from a welding operation mode to a grinding operation mode or vice versa.